The main problem is: We no longer have the geographic barriers that lead us to diverge into different races in the first place. Just as Europe is becoming increasingly mixed, with less and less pure blooded nords, or Celts. the world is also becoming mixed.

We need a Natural barrier if we are to survive. Man made barriers have never worked. How many empires have fallen due to lack of natural barriers? What makes you think it cannot happen again? Thanks to our ancestors Africans have essentially colonized the globe, and are wiping out many gene pools across the globe.

We need some sort of Natural barrier. Once the oil runs out or and Ice age emerges..... Our race will be at an advantage. Ingenuity and cohesion will be prized traits.